Running with your torso tilted too far forward can increase your risk of developing exercise-related injuries like knee and back pain, a study has warned.
Researchers led by the University of Colorado Denver examined the impact on the gait of 23 young athletes from different angles of “trunk flexion.”
Since the head, arms and trunk make up 68 percent of the body by mass, changes in trunk flexion can significantly affect lower limb motion and ground reaction forces.
And previous studies have shown that runners report flexion angles from the vertical ranging from as low as -2° to as high as 25°.
The team found that increasing trunk flexion from a natural, low angle to 30° resulted in a 28 percent increase in transfers, which is less efficient and can cause injury.
Running with your torso tilted too far forward can increase your risk of developing exercise-related injuries like knee and back pain, a study has warned. Pictured: a man is running
The study was conducted by anthropologists Anna Warrener of the University of Colorado Denver and Daniel Liberman of Harvard University.
“This was a hobbyhorse turned into a study,” Professor Warrener said.
She explained that when Professor Lieberman was preparing to run marathons, “he noticed that other people leaned too far forward when running.
This, she added, “had so much impact on their lower extremities. Our study was built to find out which ones they were.’
In their study, the researchers recruited 23 injury-free recreational runners aged 18-23 each and recorded how they walked in four 15-second trials, each with a different degree of trunk flexion than vertical – 10°, 20°, 30° and the participants . natural choice.
A key challenge the team had to overcome was making sure the runners performed at the right angle for each test.
“We had to find a way that we could reasonably make someone lean forward that wouldn’t make them so uncomfortable that they change everything about their gait,” explains Professor Warrener.
The solution lay in hanging a lightweight plastic dowel from the ceiling to just above the runner’s heads while they were using the experimental treadmill, providing a gentle guide to help the participants adopt the required posture.
The team found that increasing trunk flexion from a natural, low angle (right) to a wider angle (left) led to a 28 percent increase in transfers — which is less efficient and can cause injury.
The researchers found that as trunk flexion increased to 30°, the runner’s average stride length decreased by 13 centimeters, while stride frequency increased from 86.3 strides/min to 92.8 strides/min.
In addition, the team found that the runner’s overshoot — relative to the hip — increased by 28 percent.
“The relationship between stroke rate and stride length surprised us,” said Professor Warrener.
“We thought the more you lean forward, the further your leg should extend to keep your body mass from falling outside the support area. As a result, exceedances and stride frequency would go up.’
Instead, she added, the study revealed that “the reverse was true. The stride length became shorter and the stride frequency increased.’
Professor Warrener believes this phenomenon is caused by a decrease in the ‘air phase’ in which the leg lifts off the ground, forcing runners to take shorter strides with faster leg movements.
“Swinging your leg is very expensive when you run. Swinging it faster while leaning forward can mean higher locomotive costs,” she added.
Compared to the runner’s natural trunk flexion, higher angles led to a more flexed hip and knee joint, the researchers noted.
It also led to changes in the positioning of the runners’ feet and lower extremities, leading to a greater impact of ground reaction forces on the body.
Combined, the team said, all of these changes due to excessive trunk flexion can lead to poor running and an increased risk of injury.
However, by learning more about these phenomena, scientists can learn how runners can optimize their form for energy savings and performance.
“Most importantly, running isn’t just about what happens from the torso down — it’s a whole-body experience,” said Professor Warrener.
‘Researchers should consider the downstream effects of trunk flexion when studying gait biomechanics.’
The study’s full findings were published in the journal Human Movement Sciences.
Be careful in the gym! Nearly HALF of recreational runners injure themselves in a year, regardless of gender, age, running experience or weight, study finds
Nearly half of all recreational runners injure themselves at least once a year — regardless of age, gender, running experience or weight — according to a study.
A researcher from Sweden followed more than 200 adult regular runners over the course of a year, with a sports doctor diagnosed an injury.
Injuries seen during the study largely involved the Achilles tendons, calves and knees.
Nearly half of all recreational runners injure themselves (as pictured) at least once a year – regardless of age, gender, running experience or weight – a study has shown (stock image)
“A third of the participants were injured during the study,” says study author and sports scientist Jonatan Jungmalm of the University of Gothenburg.
But, he added, “when you also take into account the participants who dropped out of the study, it’s reasonable to assume that nearly half of all recreational runners get injured in a year.”
“Few of the injuries were long-lasting. But because of all the injuries, the runners couldn’t just train.’
In his research, Mr. Jungmalm recruited more than 200 runners aged 18-55 from the Göteborgsvarvet Half Marathon entrants list.
To participate in the study, each athlete had to run for a minimum of one year, total a minimum of 15 kilometers per week on an average of 15 kilometers and also be injury-free for the previous six months.
Each runner completed a training diary for a year and noted how far they ran and whether they experienced pain.
Injuries seen during the study largely affected the Achilles tendons, calves and knees
Participants who had sudden injuries or prolonged pain were monitored by a sports physician.
The study found that – of the runners who were injured – half developed problems with their Achilles tendons, calves or knees.
There appeared to be no difference in age, gender, weight or even running experience between runners who were injured and runners who were not injured.
But, Mr Jungmalm noted, “those who had been injured before were more likely to be hit again.”
Before participating in the study, each of the runners was subjected to a series of physical tests to determine their strength, mobility and running style.
Those with relatively weak outer thighs had a higher risk of injury. Those with late pronation in their gait were also at greater risk,” said Mr Jungmalm.
Pronation is the way the human foot rolls inward to distribute impact upon landing. Late pronation can strain the Achilles tendon and strain the calf.
“Having a weak torso or limited muscle flexibility, however, was not of great significance,” adds the sports scientist.
The full findings of Mr. Jungmalm — titled ‘Running injuries in recreational runners. How much, who and why?‘ – was defended on April 16, 2021.